Patent GB-862871-A (GB)
Title: Improvements in or relating to fastening devices for doors
IPC: E05B55/00
Filed: 1957-10-03
Abstract: 862,871. Latch fastenings. WEBSTER, D. E. C. Oct. 3, 1957 [Oct. 8, 1956], No. 31062/57. Class 44. A fastening device for doors of the kind having push button means for retraction of the latch bolt 1 and comprising a fixed casing 4 in which the latch bolt is slidably located and having one end normally extending from the casing by spring biasing means 11, the bolt being capable of retraction into the casing and along the direction of its axis by a guided operating slide 13 extending transversely through the casing and transversely between the end of the latch bolt within the casing and a perpendicular projection 3 on an extension of the end of the latch bolt, the slide providing a notch 15 presenting converging oblique faces of which at least one is slidably engaged by a complementary oblique face 16 presented by the perpendicular projection whereby on displacement of the slide in the direction of its axis on applying pressure on the push button means on one end of the slide, sliding action of one of the oblique faces of the notch 15 on the complementary face of the projection 3 causes the latch bolt to be retractably displaced into the casing, characterized in that the extension of the latch bolt, providing the perpendicular projection is of reduced width and is eccentrically disposed on the latch bolt and, with its projection 3, is located in guided slidable fashion in a reduced parallel-walled cavity presented in the casing, the biasing means 11 comprising a compression spring bearing against one portion of the bolt and on a disc 10 located within the casing and the disc providing a rounded-off projection 64 engaging a depression 63 in the side of the slide opposite to the side presenting the notch and whereby, for sliding of the slide, the disc is displaced against the action of the compression spring to restrain the sliding action of the slide. The casing 4 is cylindrical and is adapted to be positioned in a hole bored in an upright end of the door. The bolt is of generally cylindrical shape with a flat surface 6 which engages a similar face 7 in the casing 4 to prevent rotation of the bolt. The spring 11 is positioned between a face on the bolt and the disc 10 which engages shoulders 9 formed in the casing. The notch 15 in a slide 13 is V-shaped and is disposed transversely of the casing 4 and extends through openings 12 in the casing. Movement of the slide in either direction causes the bolt to be retracted. At one end of the slide a knob 24 forming one of the push button means is provided and at the other end is a hollow tubular part 19 which contains the barrel 40 of a pin tumbler barrel lock and which constitutes the other push button means. Both the barrel and the knob are connected to a wirelike locking strip 32 which can be rotated through 90 degrees by both the knob 24 and the barrel 40 and which has a U-shaped portion 33 which in its locking position engages the projection 3 and so prevents movement of the projection relative to the slide. The locking strip is contained in a groove in the slide. It is connected to the knob by means of a hook-like end 38 the tip of which engages a shoulder 28 in the knob to retain the knob on the slide. The hook-like end is contained in a radial groove 26 of the knob and engages either of two faces of the slide to retain the locking strip in its locking or non-locking positions. The opposite end of the locking strip is provided with a crank arm 36 which is engaged in a sector shaped notch 45 in the barrel 40; thus the barrel can be rotated by a key through 90 degrees to move the locking strip to its locking position and can be returned to its initial position without moving the locking strip; rotation in the opposite direction causes the movement of the locking strip to unlocking position. The slide is contained in a transverse casing 50 the ends of which are engaged by fixed handles on the door. The handles can either be a push fit on the casing 50 or can engage it by means of screw threads. In a modification the lock barrel can be omitted and in such a case only the knob is provided so that the bolt can be retracted from one side of the door only. The latch bolt can be provided with an additional projection behind the projection 3 for engaging a groove in the casing 4 to act as additional guiding means; this projection can be provided with rollers if desired.